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Personal Preparation and Storage of Safe Water

After an emergency, such as a flood, hurricane, or earthquake, drinking water may not be available or safe to drink. As a result, residents may have to find a source of safe drinking water or know how to treat their water for use in certain activities, such as drinking, making ice, washing hands, and brushing teeth. The following information will tell you how to plan for treating and storing your water in the event of an emergency.

Make Water Safe

Water often can be made safe to drink by boiling, adding disinfectants, or filtering.

IMPORTANT: Water contaminated with fuel or toxic chemicals will not be made safe by boiling or disinfection. Use a different source of water if you know or suspect that water might be contaminated with fuel or toxic chemicals.

Boiling

If you don’t have safe bottled water, you should boil water to make it safe. Boiling is the surest method to make water safer to drink by killing disease-causing organisms, including viruses, bacteria, and parasites.

You can improve the flat taste of boiled water by pouring it from one container to another and then allowing it to stand for a few hours, OR by adding a pinch of salt for each quart or liter of boiled water.

If the water is cloudy,

Filter it through a clean cloth, paper towel, or coffee filter OR allow it to settle.

Draw off the clear water.

Bring the clear water to a rolling boil for one minute (at elevations above 6,500 feet, boil for three minutes).

Disinfectants

If you don’t have safe bottled water and if boiling is not practical, you often can make small quantities of filtered and settled water safer to drink by using a chemical disinfectant such as unscented household chlorine bleach. These disinfectants can kill most harmful or disease-causing viruses and bacteria but are not as effective in controlling more resistant organisms such as the parasites Cryptosporidium and Giardia.

To disinfect water with unscented household liquid chlorine bleach:

Filter the water through a clean cloth, paper towel, or coffee filter OR allow it to settle.

Draw off the clear water.

Follow the instructions for disinfecting drinking water that are written on the label.

If the necessary instructions are not given, check the "Active Ingredient" part of the label to find the sodium hypochlorite percentage, and use the information in the following table as a guide. Typically unscented household liquid chlorine bleach will be 5.25%, 6%, or 8.25% sodium hypochlorite. Add the following amount of bleach:

% Sodium Hypochlorite

Drops per Quart/Liter/Gallon of Clear Water

If the water is cloudy, murky, colored, or very cold, double the amount of bleach added.

Follow the manufacturer’s instructions on the label or in the package.

Chlorine dioxide can be effective against Cryptosporidium if the manufacturer’s instructions are followed correctly.

Iodine and iodine-containing tablets (tetraglycine hydroperiodide) are not effective against Cryptosporidium.

Filters

Many portable water filters can remove disease-causing parasites such as Cryptosporidium and Giardia from drinking water. If you are choosing a portable water filter, try to pick one that has a filter pore size small enough to remove both bacteria and parasites. Most portable water filters do not remove viruses.

Carefully read and follow the manufacturer’s instructions for the water filter you intent to use. After filtering, add a disinfectant such as iodine, chlorine, or chlorine dioxide to the filtered water to kill any viruses and remaining bacteria. For more information about water filters, see the Water Treatment Resources section.

Distillation

You may also be able to make water safe by distilling it, or boiling water and collecting the steam in a clean container so it turns back into water.

Finding Emergency Water Sources

Alternative sources of clean water can be found inside and outside the home. DO NOT DRINK water that has an unusual odor or color, or that you know or suspect might be contaminated with fuel or toxic chemicals; use a different source of water.

The following are possible sources of water:

Inside the Home

Water from your home’s water heater tank

Melted ice cubes made with water that was not contaminated

Liquid from canned fruit and vegetables

Listen to reports from local officials for advice on water precautions in your home. It may be necessary to shut off the main water valve to your home to prevent contaminants from entering your piping system.

Outside the Home

Rainwater

Streams, rivers, and other moving bodies of water

Ponds and lakes

Natural springs

Water from sources outside the home must be treated as described in Make Water Safe. DO NOT DRINK water that has an unusual odor or color, or that you know or suspect might be contaminated with fuel or toxic chemicals; use a different source of water.